Endo-1,4-β-xylanases (E.C.3.2.1.8) depolymerize xylan by random hydrolysis of the xylan backbone. Xylan is the second most common hemicellulose found in plant cell walls after cellulose. Recently, there has been much interest in using xylan and xylanases for various purposes, e.g., as a supplement in animal feed, for the manufacture of bread, food and drinks, in pulp and paper processing, and for the pretreatment of biomass conversions to produce bioethanol.
Although xylanases from thermophilic organisms are available, they may not be suitable for industrial processes. Thus, there is a need for mutant xylanases with improved enzyme activity and thermostability.